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Temperature Effects on the Unsaturated Permeability of the Densely 1
Compacted GMZ01 Bentonite under Confined Conditions 2
3
W. M. Y E a,b,*, M. WAN a, B. CHEN a，Y. G. CHEN a，Y. J. CUI a,c, J. WANGd 4
a. Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education, Tongji 5
University, Shanghai 200092，China 6
b. United Research Center for Urban Environment and Sustainable Development, the Ministry of 7
Education, Shanghai 200092，China 8
c. UR Navier, Ecole des Ponts ParisTech, France 9
d. Beijing Research Institute of Uranium Geology, Beijing 100029，China 10
11
*To whom correspondence and reprint requests should be addressed; Tel.: +86 21 6598 3729; Fax: 12
+86 21 6598 2384, E-mail: [email protected] 13
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Author manuscript, published in "Engineering Geology 126 (2012) 1-7" DOI : 10.1016/j.enggeo.2011.10.011
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Abstract 15
In this study, temperature controlled soil-water retention tests and unsaturated hydraulic conductivity 16
tests for densely compacted Gaomiaozi bentonite - GMZ01 (dry density of 1.70 Mg/m3) were 17
performed under confined conditions. Relevant soil-water retention curves (SWRCs) and unsaturated 18
hydraulic conductivities of GMZ01 at temperatures of 40°C and 60°C were obtained. Based on these 19
results as well as the previously obtained results at 20°C, the influence of temperature on 20
water-retention properties and unsaturated hydraulic conductivity of the densely compacted 21
Gaomiaozi bentonite were investigated. It was observed that: (i) water retention capacity decreases as 22
temperature increases, and the influence of temperature depends on suction; (ii) for all the 23
temperatures tested, the unsaturated hydraulic conductivity decreases slightly in the initial stage of 24
hydration; the value of the hydraulic conductivity becomes constant as hydration progresses and 25
finally, the permeability increases rapidly with suction decreases as saturation is approached; (iii) 26
under confined conditions, the hydraulic conductivity increases as temperature increases, at a 27
decreasing rate with temperature rise. It was also observed that the influence of temperature on the 28
hydraulic conductivity is quite suction-dependent. At high suctions (s > 60 MPa), the temperature 29
effect is mainly due to its influence on water viscosity; by contrast, in the range of low suctions (s < 30
60 MPa), the temperature effect is related to both the water viscosity and the macro-pores closing 31
phenomenon that is supposed to be temperature dependent. 32
33
Key words：GMZ bentonite; nuclear waste repository; temperature; water-retention property; 34
unsaturated permeability 35
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1 Introduction 36
In a conceptual multi-barrier disposal radioactive waste repository (Figure 1), significant 37
Temperature- Hydraulic-Mechanical (THM) phenomena take place in the engineered barrier and in 38
the near field due to the combined actions of heating and hydration (Sanchez et al, 2004). The 39
hydraulic property of the compacted bentonite used as engineered barrier material is one of the key 40
properties for the design of such a disposal system. This explains the large number of studies that 41
have been performed in this area: Dixon et al (1987), Nachabe (1995) and Liu and Wen (2003) tested 42
the permeability of saturated compacted bentonites and analyzed the related influencing factors; Villar 43
(2000, 2002) and Komine (2004) reported different empirical relations between dry density and 44
saturated permeability of compacted benonite; Komine (2004) and He and Shi (2007) predicted the 45
saturated permeability of bentonite based on the changes in porosity. For the unsaturated bentonite, 46
after an investigation to the unsaturated permeability of the mixture of the Kunigel V1 bentonite and 47
Hostun sand under confined conditions, Loiseau (2001) found that for suction lower than 23MPa, the 48
unsaturated permeability increases with suction decrease, while for suction higher than 23MPa, the 49
unsaturated permeability decreases as suction decreases. Under both confined conditions and 50
unconfined conditions, Cui et al. (2008) tested the unsaturated permeability of the mixture of 51
Kunigel-V1 bentonite/Hostun sand based on the instantaneous profile method, and found that as 52
suction decreases, the unsaturated permeability decreases to a certain value and then turns to increase. 53
Cho et al. (1999) reported that the influence of temperature on the permeability of bentonite is 54
mainly because the intrinsic permeability, viscosity and density of water are influenced by 55
temperature. Changes in viscosity of water with temperature have been found to be the most 56
important mechanism (Towhata et al, 1993; Cho et al, 2000; and Villar and Lloret, 2004). 57
GMZ bentonite has been selected as the potential buffer/backfill material for the construction of 58
the engineered barrier in the Chinese deep geological disposal program for high level radioactive 59
nuclear waste, thanks to its high montmorillonite content, high cation exchange capacity (CEC), large 60
specific surface and other desirable properties (Liu and Wen, 2003). Studies on the mineralogy and 61
chemical composition, mechanical properties, hydraulic behavior, swelling behavior, thermal 62
conductivity, microstructure and volume change behavior of the GMZ bentonite have been conducted 63
over years (Ye et al., 2010b). The investigation of the hydraulic properties of the GMZ bentonite has 64
been the gravity center of the recent studies. Liu and Wen (2003) tested the saturated permeability and 65
analyzed the related influencing factors of the compacted GMZ bentonite. Using the instantaneous 66
profile method, Ye et al. (2010a) tested the unsaturated permeability of the densely compacted 67
specimen, with a dry density of 1.7Mg/m3, under confined (constant-volume) conditions. Results 68
show that the unsaturated hydraulic conductivity of the compacted bentonite changes from 1.13×10-13 69
m/s to 8.41×10-15 m/s (gravimetric water content from 12% to 28%) and it is not solely function of 70
suction. While under unconfined (free-swelling) conditions, the unsaturated hydraulic conductivity of 71
the Gaomiaozi bentonite is in a larger range of 1.0×10-12 - 1.0×10-15 m/s. Based on the 72
Kozeny–Carmen semi-empirical function, Niu et al (2009) proposed a semi-empirical equation for the 73
calculation of the unsaturated permeability of the GMZ bentonite with the consideration of 74
micro-structural changes. 75
As far as the influence of temperature effect is concerned, Ye et al. (2009b) reported that the 76
water retention capacity of the highly-compacted GMZ bentonite and bentonite-based mixtures 77
decreases as the temperature increases, regardless of the confining conditions. 78
In this paper, the soil-water retention curves (SWRCs) of the densely compacted Gaomiaozi 79
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bentonite (GMZ01) under confined conditions and at various temperatures (20°C, 40°C and 60°C) are 80
presented. Based on the results obtained, the unsaturated permeability of the GMZ01 is investigated 81
by performing infiltration tests under controlled temperature. 82
2. Materials 83
The Gaomiaozi deposit is located in the northern Chinese Inner Mongolia autonomous region, 84
300 km northwest from Beijing (Ye et al., 2009a, 2010b). Some basic properties of the GMZ01 85
bentonite tested in this paper are listed in Table 1, which indicates that the GMZ01 bentonite has high 86
cation exchange capacity and high adsorption ability. 87
3 Experimental Methods 88
The instantaneous profile method has been adopted in this study. This method was successfully 89
used by many researchers to determine the unsaturated hydraulic conductivity of geomaterials (Daniel, 90
1982；Richards and Weeks, 1953; Hamilton et al., 1981; Watson, K.K., 1966; Meerdink et al., 1996; 91
Fujimaki and Inoue, 2003; Cui et al., 2008; Ye et al., 2010a). As an unsteady-state method, it can be 92
used either in the laboratory or in situ (Benson and Gribb 1997). 93
In order to apply this method to determine the unsaturated permeability of the GMZ01 bentonite 94
at different temperatures, on the one hand, the SWRCs of this soil should be determined at relevant 95
temperatures, and on the other hand, the corresponding suction profiles should be determined by 96
performing infiltration test at different temperatures with suction monitoring. For a given temperature, 97
the hydraulic gradient was determined using the suction profile; the water flux was determined using 98
the water content profile; the hydraulic conductivity was then calculated based on the generalized 99
Darcy’s law. The detailed calculation procedure can be found in Ye et al. (2009a). 100
101
3.1 Determination of SWRCs 102
3.1.1 Suction control 103
The vapour equilibrium technique (for high suctions) and osmotic technique (for low suctions) 104
were employed for suction control in this study. At high suctions, the experimental setup used was 105
described by Ye et al (2005), as shown in Fig.2. Note that the vapor equilibrium technique was 106
employed by number of researchers for controlling total suction in unsaturated soil tests (Bernier et al, 107
1997; Blatz and Graham, 2000; Lloret et al, 2003; Chen et al, 2006). 108
In this study, the confined GMZ01 specimen was placed in a desiccator and the water vapour 109
above a saturated salt solution was circulated to provide the desired suction to the specimen. Saturated 110
salt solutions and their corresponding suctions imposed at 20, 40 and 60°C are shown in Table 3 111
(Tang and Cui, 2005). 112
For low suctions, the osmotic technique was used and the corresponding setup is shown in Fig 3 113
(Delage et al., 1992; 1998). Note that Tang et al. (2010) studied the temperature effect on the 114
calibration curve of PEG solutions and found that this effect is insignificant. Thus, in this study, the 115
osmotic technique was employed without temperature correction. 116
117
3.1.2 Apparatus 118
Custom-designed stainless steel cells with small holes in two ends (Fig.2, Ye, 2009a) were 119
employed for water retention test under confined conditions. The holes were designed as channels for 120
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moisture exchange between the specimen in the cell and the circulating air (or PEG solution) around it. 121
For the temperature control, the setups were placed in ovens (Fig 3 and Fig 4), which have 122
temperature controlled to an accuracy of ±0.1°C. Note that temperatures of 20, 40 and 60°C were 123
selected as the testing temperatures in this study. 124
3.1.3 Specimen preparation 125
The GMZ01 bentonite powder was compacted into a thin cylindrical specimen, which has a final 126
dimension of 20 mm in diameter and 6 mm in height. For the compaction, a press was used and the 127
compaction was carried out at a velocity of 0.1 mm/min. The final dry density and water content of 128
the compacted specimen were 1.70g/cm3 and 10.65%, respectively. 129
3.2 Infiltration test 130
The schematic layout of the temperature controlled infiltration test is shown in Fig.5. A 131
custom-designed cylinder (Ye et al., 2009a, 2010a) is put in an oven with temperature controlled to an 132
accuracy of ±0.1°C. The resistive relative humidity (RH) sensors (Cui et al, 2008) were used to 133
monitor the RH changes. Note that the same type of sensor was used by Ye et al. (2009a, 2010a). It 134
can be seen from Fig.5 that the sensors were installed every 30 mm along the length of the cell (4 135
sensors) with a fifth sensor in the upper base plate of the cell. As the sensors measure the air relative 136
humidity, no direct contact with soil specimen was allowed. For this reason, a small cavity was bored 137
in the soil for each transducer. This cavity had a dimension allowing introducing the transducer cap: a 138
porous stone of 2 mm thick and 5 mm in diameter. This porous stone separated the transducer from 139
the soil sample and allowed the air humidity transfer from the specimen to the transducer (Ye et al., 140
2009a). 141
The distilled water was used in the infiltration test. The water absorbed by the specimen can be 142
quantified by calculating the water volume change in the left marked glass pipe, which can be 143
compensated by water from the right tube, in the U-shaped system outside the oven. Two drops of 144
silicone oil were added into the left pipe to prevent water evaporation. A soft tube was used for 145
connecting the U-shaped system to the inlet of the specimen in order to warm up the water to current 146
testing temperature before absorption. The humidity and temperature changes were recorded by the 147
data logging system. 148
A double-piston mould was used for the compaction of the specimen (Cui and Delage, 1996). 149
The powder of the GMZ01 bentonite was compacted in 5 layers. After the first layer (30 mm) was 150
compacted and the surface of specimen was carefully scarified for the integrity of the specimen, the 151
equal parts of the GMZ01 powder were added from two ends of the mould and then compacted to two 152
15 mm sub-layers. This procedure was repeated for the other 3 layers. The compaction was conducted 153
at a speed of 0.1 mm/min. The specimen has a final height of 150 mm, a dry density of 1.70 Mg/m3, a 154
suction about 90 MPa for 40°C temperature and 100MPa for 60°C temperature, and a degree of 155
saturation around 0.49 for 40°C temperature and 0.41 for 60°C temperature. 156
The unsaturated permeability test on the GMZ01 bentonite at 20°C was previously measured and 157
reported by Ye et al. (2010) and thus only the infiltration tests at temperatures of 40°C and 60°C were 158
performed in this study. 159
160
4. Results and discussion 161
4.1 SWRCs 162
The SWRCs of the highly-compacted GMZ01 specimen following wetting path at different 163
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temperatures (20°C, 40°C and 60°C) under confined conditions are shown in Fig.5. Based on these 164
results, an equation can be proposed to describe the water retention curves of the densely compacted 165
GMZ01 bentonite (1.7 Mg/m3): 166
{ }cb
sat
a
ww
])(72.2ln[ ψη
+= （1） 167
with 168
r
r
ψ
ψψ
η1000
1
)1ln(
1+
+−= ， (2) 169
Where ψ (MPa) is the suction; rψ (MPa) is a reference suction (309 MPa in this study); wsat is the 170
water content in the saturated state: ( )4.2732000018.025.0 −−+= Twsat ; T (K) is the absolute 171
temperature; a (MPa), b and c are soil parameters: 395.20)273(1474.4 +−−= TLna ; b = 0.8086 ; 172
c = 0.5864. 173
Fig.6 indicates that, the water retention capacity decreases as temperature increases and the 174
degree of the temperature influence depends on suction. This phenomenon can be analyzed separately 175
at low and high suctions. At high suctions (> 4 MPa), changes of clay fabric and fluid in 176
intra-aggregate spaces play a significant role in water retention capacity of GMZ bentonite. 177
Intra-aggregate water moves into macro-pores (inter-aggregates pores) with temperature increase (Ye 178
et al, 2009a). This process decreases the suction in the macro-pore level. As the suction is controlled, 179
water flows out from the macro-pores, leading to a decrease of water retention capacity. At low 180
suctions, capillary effect plays a decisive role in the water retention capacity. Increase of temperature 181
causes changes in surface tension, which results in decrease of water content under constant suction 182
conditions. 183
In order to quantitatively assess the influence of temperature on the water retention capacity of 184
the bentonite under different suctions, a ratio kT is defined as follows: 185
%1001
21 ×−=T
TTT w
wwk (3) 186
where wT1 and wT2 are water content at temperature T1 and T2 respectively for the same suction. 187
The relationship between the ratio kT and suction for the GMZ01 bentonite at 40°C and 60°C are 188
given in Fig.7. It can be observed that the effect of temperature on the water retention capacity is 189
closely related to suction, particularly in the range from 30 to 60 MPa. This effect reaches a maximum 190
at a suction around 40 MPa. 191
4.2 Unsaturated permeability 192
4.2.1 Test at 40°C 193
The relative humidity changes with hydration time in the infiltration test at 40°C are shown in 194
Fig.8. Based on the SWRCs measured at 40°C (see Fig.6), the development of suction with hydration 195
time can be obtained. Note that the conversion from relative humidity to suction was done using the 196
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Kelvin’s law. Fig 8 indicates that, for the relative humidity sensor located 3 cm from the hydration 197
water inlet at the bottom of the specimen, suction decreases rapidly in the first 200 h of hydration and 198
then decreases much more slowly. For suction measured at 6 cm, it begins to decrease rapidly after 199
100 h hydration and gradually decreases after 800 h hydration. As it is relatively far from the water 200
inlet, suctions measured at 12 cm and 15 cm from the bottom of the specimen start to decrease rapidly 201
after 200 and 300 h of hydration, respectively. The slope of the curve of suction versus time decreases 202
as the distance from the inlet increases. The test was stopped after about 1670 h hydration, when the 203
sensor at 3 cm distance from the inlet indicated that zero suction (100% relative humidity) was 204
achieved at this height. 205
The relationship between the unsaturated hydraulic conductivity and suction is shown in Fig.9. It 206
can be observed that at 40°C temperature, the unsaturated hydraulic conductivity of the GMZ01 with 207
a dry density of 1.7 Mg/m3 is on the whole between 1.64×10-13m/s and 1.34×10-14m/s. During the 208
initial stages of hydration, the hydraulic conductivity gradually decreases with suction decrease, and 209
the hydraulic conductivity reaches the minimum value of 1.34×10-14m/s when the suction drops to 210
45 MPa; the hydraulic hydraulic conductivity keeps steady in the range of suction from 20 MPa to 211
60MPa; but when suction drops to a level lower than 20 MPa, the unsaturated hydraulic conductivity 212
increases rapidly and reaches 1×10-13m/s. 213
4.2.2 Test at 60°C 214
The unsaturated hydraulic conductivity of the confined GMZ01 determined at 60°C is shown in 215
Fig.10. It can be seen that the values are generally between 1.79×10-14m/s and 1.19×10-13m/s. As the 216
infiltration of water progresses, suction drops from 80 MPa to 55 MPa, while the unsaturated 217
hydraulic conductivity decreases slightly. With suction reduction from 55 MPa to 20 MPa, the 218
hydraulic conductivity remains almost constant despite of the suction changes. For suction lower than 219
20 MPa, the hydraulic conductivity rapidly increases with decreasing suction and reaches a final value 220
of 1×10-13m/s. 221
When the soil suction is decreased from the initial value (about 80 MPa) to zero, the hydraulic 222
conductivity first decreases from 2×10–14m/s to 7×10–15m/s and then increases to 1×10–13m/s, which is 223
close to the saturated hydraulic conductivity. As in the first stage, water transfer is primarily governed 224
by the network of large pores and these large pores are progressively decreasing in quantity and in 225
size, resulting in hydraulic conductivity decreases. After completion of this large-pore clogging by gel 226
creation, a normal conductivity increase with suction decrease is observed (Ye et al., 2009a). 227
4.3 Influence of temperature on the unsaturated hydraulic conductivity 228
To further assess the influence of temperature on the unsaturated permeability of the highly 229
compacted GMZ01 bentonite, the unsaturated hydraulic conductivity of the confined specimen at 230
20°C (Ye et al, 2009a) are compared to those measured at 40°C and 60°C (Fig.11). It can be seen that 231
under confined conditions, the unsaturated hydraulic conductivity of the highly compacted GMZ01 232
bentonite increases with temperature rise. Moreover, the rate of change also decreases as temperature 233
increases. The temperature effect becomes more significant at higher suctions (above 20 MPa). In the 234
range of lower suctions (less than 20 MPa), it is observed that the lower the suction the less the 235
temperature effect. The possible explanation is that for lower suctions the moisture absorbed by the 236
bentonite is mainly associated with microstructure changes and the temperature effect on the 237
microstructure is not significant. 238
The influence of temperature on the hydraulic conductivity is mainly related to the influence of 239
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temperature on the water viscosity and the pore structure of the bentonite. To remove the influence of 240
temperature on water viscosity, the relative hydraulic conductivity is introduced to allow for a better 241
analysis of the influence of temperature on hydraulic conductivity. Relationships between the relative 242
permeability and degree of saturation (Sr) of the confined GMZ01 at 40°C and 60°C are given in 243
Fig.12. It can be observed that when Sr is higher than 0.57, the hydraulic conductivity at 60°C is 244
similar to that observed at 40°C. This means that in this range of degree of saturation the influence of 245
temperature on permeability is mainly due to the influence on water viscosity. On the contrary, when 246
Sr is lower than 0.57, the relative permeability at 40°C is found higher than that at 60°C. Interestingly, 247
this threshold corresponds to a suction of 60 MPa, and from Figs 9, 10 and 11 it can be observed that 248
when s > 60 MPa the hydraulic conductivity decreases with suction decrease. As mentioned above, in 249
this suction range hydration leads to progressive macro-pores closing thus to a decrease in hydraulic 250
conductivity. This macro-pore closing process can be assumed to be more significant at higher 251
temperature because of softer clay aggregates and lower water viscosity, explaining a lower hydraulic 252
conductivity at 60°C than at 40°C. As the relative hydraulic conductivity has been found independent 253
of temperature when Sr > 0.57 (Fig. 12), it can be supposed that the macro-closing process ended 254
when Sr > 0.57; in other words, the influence of temperature on pore structure became insignificant in 255
this range. 256
It is also important to note that the obtained results could be affected by the possible density 257
gradient along the specimen as identified by Dixon et al. (2002) and Villar et al. (2008). This density 258
gradient can be formed owing to the expansion of the hydrated bentonite that intrudes into the drier 259
area under the effect of swelling pressure. If it occurs, the computation of degree of saturation without 260
considering this gradient is not correct and the water retention curve considered is also inappropriate. 261
In other words, the simultaneous profile method meets its limitation. Because in this study, no specific 262
analyses were conducted after the infiltration tests, this phenomenon can not be verified. Further 263
studies will be performed to investigate this aspect. 264
265
5 Conclusions 266
The SWRCs of the highly compacted GMZ01 confined specimens on wetting path and at 267
different temperatures (20°C, 40°C and 60°C) show that the water retention capacity decreases as 268
temperature increases; and the influence of temperature depends on suction. The ratio kT can be used 269
to quantitatively describe the influence of temperature on water retention capacity of bentonite at 270
different suctions. 271
Under confined conditions and at 40°C temperature, the unsaturated hydraulic conductivity of 272
the GMZ01 bentonite at a dry density of 1.7Mg/m3 is between 1.64×10-13m/s and 1.34×10-14m/s. At 273
60°C temperature, the value is slightly lower, between 1.19×10-13m/s and 1.79×10-14m/s. 274
For all the temperatures considered, the unsaturated hydraulic conductivity decreases slightly in 275
the first stage of hydration. The value of the hydraulic conductivity becomes constant as hydration 276
progresses. Finally, the hydraulic conductivity increases rapidly with suction decreases when 277
saturation is approached. This phenomenon may be explained by the changes in the soil 278
microstructure. 279
Under confined conditions, the hydraulic conductivity increases as temperature increases, at a 280
rate that decreases with temperature rise. Also, the influence of temperature on the hydraulic 281
conductivity is quite suction-dependant. At high suctions (s > 60 MPa) or low degrees of saturation 282
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(Sr < 0.57), the temperature effect is mainly due to its influence on water viscosity; on the contrary, in 283
the range of low suctions (s < 60 MPa) or high degrees of saturation (Sr > 0.57), the temperature 284
effect is related to both the water viscosity and the macro-pores closing phenomenon that is supposed 285
to be temperature dependent. Note that further studies are needed to investigate the possible dry 286
density gradient effect on the hydraulic conductivity determined based on the simultaneous profile 287
method. 288
289
ACKNOWLEDGEMENTS 290
The authors are grateful to the National Natural Science Foundation of China (Projects No. 291
41030748, No.40772180 and No.40728003), Kwang-Hua Fund for College of Civil Engineering at 292
Tongji University, China Atomic Energy Authority (Project [2007]831), and Shanghai municipality 293
(Leading Academic Discipline Project - B308). 294
295
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Table 1 Basic Properties of GMZ01 bentonite 391
Property Description
Specific gravity of soil 2.66 pH 8.68−9.86
Liquid limit (%) 276 Plastic limit (%) 37
Total specific surface area/
(m2·g−1)
570
Cation exchange capacity/
(mmol·g−1) 0.773 0
Main exchanged cation/
(mmol·g−1)
Na+(0.433 6), Ca2+(0.291 4), Mg2+(0.123 3),
K+(0.025 1)
Main minerals
Montmorillonite(75.4%), quartz (11.7%), feldspar (4.3%),
cristobalite (7.3%) 392
393
Table 2 Salt solution and corresponding suction at different temperatures (MPa)(Tang 2005) 394
Salt solution 20°C 40°C 60°C
LiCl 2 309.0 − 340
MgCl2 150.0 162.4 187.7
K2CO3 113.0 122.0 144.8
Mg(NO3)2 82.0 103.1 139
NaNO2 57.0 −
NaNO3 39.0 49.5 61.6
NaCl 38.0 40.6 44.2
(NH4)2SO4 24.9 32.2
KCl 21.0 27.8 33.4
ZnSO4 12.6 −
KNO3 9.0 −
K2SO4 4.2 5.1 5.5
395
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Compacted bentonite
HLW
Host rock
Canister
396 Fig. 1. Schematic view of a high level nuclear waste repository (Sanchez, 2004) 397
398
399
400
Fig. 2. Constant-volume hydration cell 401
402
403 Fig. 3. Setup for the water retention curve determination using the vapor equilibrium technique 404
405
PolyethyleneMembrane
Semi-permeableMembrane
Specimen
PEG20000 Solution
Magnetic Stirrer
Oven(temperature Control ¡ À0.1℃)
Porous Stone
Rubber RingSteel Bracket
406
Fig. 4. Setup for the water retention curve determination using the osmotic technique 407
408
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Data Logger
Humidity Sensor
Oven(Temperature Control± 0.1℃)
Compacted Bentonite
Porous Stone Valve
Water Level
409
Fig. 5. Schematic layout of the temperature controlled infiltration test 410
0
4
8
12
16
20
24
28
0.01 0.1 1 10 100 1000Suction /MPa
w /% Measured (60℃℃℃℃)
Measured (40℃℃℃℃)
Measured (20℃℃℃℃)
Caculated (20℃℃℃℃)
Caculated (40℃℃℃℃)
Caculated (60℃℃℃℃)
411 Fig. 6. Water retention curves of the confined specimen at different temperatures 412
413
0000
5555
10101010
15151515
1111 10101010 100100100100 1000100010001000Suction /MPa
k T
/%
40-60℃℃℃℃20-60℃℃℃℃20-40℃℃℃℃
414
Fig. 7. Change of KT with suction 415
416
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15
40
50
60
70
80
90
100
0 200 400 600 800 1000 1200 1400 1600 1800
Time(h)
Hu
mid
ity(%
)
15cm
12cm
9cm
6cm
3cm
417 Fig. 8. Evolution of the relative humidity of confined GMZ01 with time at 40°C 418
1.E-15
1.E-14
1.E-13
1.E-12
0 10 20 30 40 50 60 70 80Suction(MPa)
K(m
/s)
3cm
6cm
9cm
Fitted Curve
419 Fig. 9. Change of unsaturated hydraulic conductivity with suction for the confined GMZ01 at 40°C 420
1.E-15
1.E-14
1.E-13
1.E-12
0 10 20 30 40 50 60 70 80
Suction(MPa)
K(m
/s)
3cm
6cm
9cm
Fitted Curve
421
Fig. 10. Change of unsaturated hydraulic conductivity with suction for the confined GMZ01 at 60°C 422
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1.0E-15
1.0E-14
1.0E-13
1.0E-12
0 10 20 30 40 50 60 70 80Suction(MPa)
K(m
/s)
20℃40℃60℃
423 Fig. 11. Evolution of unsaturated hydraulic conductivity with suction for the confined GMZ01 at 424
different temperatures 425
426
0.0
0.1
1.0
0.4 0.5 0.6 0.7 0.8 0.9 1Sr
Kr
(m/s
)
3cm 40℃℃℃℃3cm 60℃℃℃℃
427
Fig. 12. Relationship between Kr and Sr of the confined GMZ01 at 40°C and 60°C 428
429
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